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### What changes were proposed in this pull request? This PR proposes: 1. To introduce `InheritableThread` class, that works identically with `threading.Thread` but it can inherit the inheritable attributes of a JVM thread such as `InheritableThreadLocal`. This was a problem from the pinned thread mode, see also https://github.com/apache/spark/pull/24898. Now it works as below: ```python import pyspark spark.sparkContext.setLocalProperty("a", "hi") def print_prop(): print(spark.sparkContext.getLocalProperty("a")) pyspark.InheritableThread(target=print_prop).start() ``` ``` hi ``` 2. Also, it adds the resource leak fix into `InheritableThread`. Py4J leaks the thread and does not close the connection from Python to JVM. In `InheritableThread`, it manually closes the connections when PVM garbage collection happens. So, JVM threads finish safely. I manually verified by profiling but there's also another easy way to verify: ```bash PYSPARK_PIN_THREAD=true ./bin/pyspark ``` ```python >>> from threading import Thread >>> Thread(target=lambda: spark.range(1000).collect()).start() >>> Thread(target=lambda: spark.range(1000).collect()).start() >>> Thread(target=lambda: spark.range(1000).collect()).start() >>> spark._jvm._gateway_client.deque deque([<py4j.clientserver.ClientServerConnection object at 0x119f7aba8>, <py4j.clientserver.ClientServerConnection object at 0x119fc9b70>, <py4j.clientserver.ClientServerConnection object at 0x119fc9e10>, <py4j.clientserver.ClientServerConnection object at 0x11a015358>, <py4j.clientserver.ClientServerConnection object at 0x119fc00f0>]) >>> Thread(target=lambda: spark.range(1000).collect()).start() >>> spark._jvm._gateway_client.deque deque([<py4j.clientserver.ClientServerConnection object at 0x119f7aba8>, <py4j.clientserver.ClientServerConnection object at 0x119fc9b70>, <py4j.clientserver.ClientServerConnection object at 0x119fc9e10>, <py4j.clientserver.ClientServerConnection object at 0x11a015358>, <py4j.clientserver.ClientServerConnection object at 0x119fc08d0>, <py4j.clientserver.ClientServerConnection object at 0x119fc00f0>]) ``` This issue is fixed now. 3. Because now we have a fix for the issue here, it also proposes to deprecate `collectWithJobGroup` which was a temporary workaround added to avoid this leak issue. ### Why are the changes needed? To support pinned thread mode properly without a resource leak, and a proper inheritable local properties. ### Does this PR introduce _any_ user-facing change? Yes, it adds an API `InheritableThread` class for pinned thread mode. ### How was this patch tested? Manually tested as described above, and unit test was added as well. Closes #28968 from HyukjinKwon/SPARK-32010. Authored-by: HyukjinKwon <gurwls223@apache.org> Signed-off-by: HyukjinKwon <gurwls223@apache.org> |
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Apache Spark
Spark is a unified analytics engine for large-scale data processing. It provides high-level APIs in Scala, Java, Python, and R, and an optimized engine that supports general computation graphs for data analysis. It also supports a rich set of higher-level tools including Spark SQL for SQL and DataFrames, MLlib for machine learning, GraphX for graph processing, and Structured Streaming for stream processing.
Online Documentation
You can find the latest Spark documentation, including a programming guide, on the project web page. This README file only contains basic setup instructions.
Building Spark
Spark is built using Apache Maven. To build Spark and its example programs, run:
./build/mvn -DskipTests clean package
(You do not need to do this if you downloaded a pre-built package.)
More detailed documentation is available from the project site, at "Building Spark".
For general development tips, including info on developing Spark using an IDE, see "Useful Developer Tools".
Interactive Scala Shell
The easiest way to start using Spark is through the Scala shell:
./bin/spark-shell
Try the following command, which should return 1,000,000,000:
scala> spark.range(1000 * 1000 * 1000).count()
Interactive Python Shell
Alternatively, if you prefer Python, you can use the Python shell:
./bin/pyspark
And run the following command, which should also return 1,000,000,000:
>>> spark.range(1000 * 1000 * 1000).count()
Example Programs
Spark also comes with several sample programs in the examples
directory.
To run one of them, use ./bin/run-example <class> [params]
. For example:
./bin/run-example SparkPi
will run the Pi example locally.
You can set the MASTER environment variable when running examples to submit
examples to a cluster. This can be a mesos:// or spark:// URL,
"yarn" to run on YARN, and "local" to run
locally with one thread, or "local[N]" to run locally with N threads. You
can also use an abbreviated class name if the class is in the examples
package. For instance:
MASTER=spark://host:7077 ./bin/run-example SparkPi
Many of the example programs print usage help if no params are given.
Running Tests
Testing first requires building Spark. Once Spark is built, tests can be run using:
./dev/run-tests
Please see the guidance on how to run tests for a module, or individual tests.
There is also a Kubernetes integration test, see resource-managers/kubernetes/integration-tests/README.md
A Note About Hadoop Versions
Spark uses the Hadoop core library to talk to HDFS and other Hadoop-supported storage systems. Because the protocols have changed in different versions of Hadoop, you must build Spark against the same version that your cluster runs.
Please refer to the build documentation at "Specifying the Hadoop Version and Enabling YARN" for detailed guidance on building for a particular distribution of Hadoop, including building for particular Hive and Hive Thriftserver distributions.
Configuration
Please refer to the Configuration Guide in the online documentation for an overview on how to configure Spark.
Contributing
Please review the Contribution to Spark guide for information on how to get started contributing to the project.